When Blair woke up that morning, an arm was laid protectively, lovingly, possessively over her waist. That goddamn sexy arm half exposed, with his shirt unbuttoned, had the most expensive watch known to the UES on its wrist and that and the fact she knew exactly how his leg felt under her thigh tipped her off about her companion before she saw his face with that ruffled hair she wanted to feel.
When later Blair was triumphing over her and Chuck's masterly plan to bring down Georgina, she was unsettled by that breathless reference to a certain fateful night said as though he couldn't help himself when she touched him even through his suit and that as well as the fact the unacknowledged truth hurt almost like a caress made her become so violent. He deserved it and she deserved that witty comeback.
When Blair watched so unsurely at first the best man's speech, she couldn't help be reminded of that perfect perfect perfect night when he raised his glass to her when it was her on show for him, all for him instead. And when he grabbed her to dance, just like Cotillion, after she had gone to him, desperate to know, she was not sure what she wanted to hear but she'd already heard enough to not need anymore.
When hetold her she did not belong with Nate, she replied with her hand already stroking the hair at the nape of his neck quite rightly she feared that he belonged with no-one and thought of her favourite film where belonging to no one never stopped Holly falling in wonderfully requited love to distract herself from an approaching Serena and all those reminders of how unperfect, unplanned this was.
When he revealed his romantic side, she did not believe him because they couldn't take it slow because they were already in so deep and if she didn't have him right now, she knew she wouldn't be able to breathe for much longer.
When Chuck pushed into her, she couldn't breathe anyway and couldn't quite see the necessity of the whole enterprise to be honest, because she wanted to tell him that she loved him so much and wanted him so much that she couldn't restrain it even if she wanted it to stop.